Rooting Characteristics of Apple Rootstocks at Two NC-140 Trial Locations

Abstract

Root distribution of nine apple rootstocks at the Michigan and Ohio sites for the 1980 NC-140 Uniform Apple Regional Rootstock Trial was determined using the trench profile method. Cultural practices and training systems were similar at the two sites. The two locations differed greatly in soil type, a Marlette fine sandy loam at Michigan and a Canfield silt loam with a fragipan at Ohio. Roots were counted and separated into three size categories: less than 2 mm in diameter, 2 to 5 mm in diameter and greater then 5 mm in diameter. Number of roots counted per tree could be separated into 3 rootstock groups for the Michigan location: MAC.24 with the most roots counted per tree; OAR 1, M.26 EMLA and M.9 EMLA as the intermediate group; and M.7 EMLA, O.3, M.9, MAC.9 and M.27 EMLA with the least. In Ohio MAC.24 was the only rootstock that was clearly distinguishable from the others. Percent of roots was greatest for all rootstocks at both locations for the less than 2 mm size and least for the greater than 5 mm size. Percent of roots smaller than 2 mm was greater at the Michigan than the Ohio location. Percent of roots in the 2 to 5 mm and the greater than 5 mm categories was greater for the Ohio than the Michigan location.